Abstract: Encarsia Forster consists of important parasitoids of whitefly (Bemisia tabaci) pests, including E. bimaculata, E. formosa and E. sophia, the three most important aphelinid parasitoids in China. Eight populations of Encarsia from the South, Southeast, North and Southwest of China, as well as two populations from Malaysia and Egypt, respectively, were collected in the present study, and their inter-species phylogenetic relationships were analyzed based on 28S rRNA D2 and D3 expansion regions. The D2 and D3 regions were consistent with each other, confirmed a closer genetic relationship between E. sophia and E. bimaculata since they both belong to the Encarisa strenus species group, compared to those between these two species and En. formosa. Results of the genetic distance analysis using 28S rRNA D2 sequences revealed that there are certain genetic divergences within single species of the Encarsia parasitoids. The Guangzhou population of Encarsia sophia is more close to populations from Australia, Spain, Egypt and Ethiopia, but further from the population from Thailand. E. bimaculata populations from Sudan, Egypt and Guatemala as well as one population from Australia cluster together, while E. formosa Hengshui and Kunming populations cluster together with those from USA, UK and Greece, but are further from the Egypt population. The reasons for the inconsistency between the genetic and geographical distances of the Encarsia species are discussed.

Key words: Aphelinidae; Encarsia, 28S rRNA, genetic distance, phylogeny, Bemisia tabaci